Nando Theeßen

README.md

@@ -25,18 +25,17 @@ When you get to the prompt, you can type `.help` for commands.
 
 Some helpful ones:
 
-* `.mode column` turn on column output for `SELECT`.
-* `.header on` turn on column headers for `SELECT`.
-* `.read filename` execute the SQL in `filename`.
-* `.open dbname` re-open a memory-only DB to a persistent file.
-* `.quit` exit SQLite. (Note that if you're using a memory-only DB, all
+- `.mode column` turn on column output for `SELECT`.
+- `.header on` turn on column headers for `SELECT`.
+- `.read filename` execute the SQL in `filename`.
+- `.open dbname` re-open a memory-only DB to a persistent file.
+- `.quit` exit SQLite. (Note that if you're using a memory-only DB, all
   data is lost at this point.)
 
 Another potentially useful third-party tool is [DB Browser for
 SQLite](https://sqlitebrowser.org/), a GUI-based SQLite viewer and data
 manipulator that can also run SQL queries.
 
-
 ## Create a Music Database
 
 Make an albums table to hold album information:
@@ -58,80 +57,86 @@ CREATE TABLE artist (
 );
 ```
 
-
 ### Exercises, Day 1
 
 Before you begin, look at the queries in `setup.sql` to get a hint as to the
 column names in the following tables. We'll use `setup.sql` later.
 
-* Create a table called `track` that holds information about a music track. It should contain:
-  * An autoincrementing `id`
-  * A title (of type `VARCHAR`, probably)
-  * A reference to an `id` in table `album` (the album the track is on). This
+- Create a table called `track` that holds information about a music track. It should contain:
+
+  - An autoincrementing `id`
+  - A title (of type `VARCHAR`, probably)
+  - A reference to an `id` in table `album` (the album the track is on). This
     should be a _foreign key_.
 
-* Create a table called `artist_album` to connect artists to albums. (Note that
+- Create a table called `artist_album` to connect artists to albums. (Note that
   an artist might have several albums and an album might be created by multiple
   artists.)
-  * Use foreign keys for this, as well.
-
-* Run the queries in the file `setup.sql`. This will populate the tables.
-  * Fix any errors at this point by making sure your tables are correct.
-  * `DROP TABLE` can be used to delete a table so you can recreate it with
+
+  - Use foreign keys for this, as well.
+
+- Run the queries in the file `setup.sql`. This will populate the tables.
+
+  - Fix any errors at this point by making sure your tables are correct.
+  - `DROP TABLE` can be used to delete a table so you can recreate it with
     `CREATE TABLE`.
 
-* Write SQL `SELECT` queries that:
-  * Show all albums.
-  * Show all albums made between 1975 and 1990.
-  * Show all albums whose names start with `Super D`.
-  * Show all albums that have no release year.
+- Write SQL `SELECT` queries that:
 
-* Write SQL `SELECT` queries that:
-  * Show all track titles from `Super Funky Album`.
-  * Same query as above, but rename the column from `title` to `Track_Title` in
+  - Show all albums.
+  - Show all albums made between 1975 and 1990.
+  - Show all albums whose names start with `Super D`.
+  - Show all albums that have no release year.
+
+- Write SQL `SELECT` queries that:
+
+  - Show all track titles from `Super Funky Album`.
+  - Same query as above, but rename the column from `title` to `Track_Title` in
     the output.
 
-  * Select all album titles by `Han Solo`.
+  - Select all album titles by `Han Solo`.
 
-  * Select the average year all albums were released.
+  - Select the average year all albums were released.
 
-  * Select the average year all albums by `Leia and the Ewoks` were released.
+  - Select the average year all albums by `Leia and the Ewoks` were released.
 
-  * Select the number of artists.
+  - Select the number of artists.
 
-  * Select the number of tracks on `Super Dubstep Album`.
+  - Select the number of tracks on `Super Dubstep Album`.
 
 ### Exercises, Day 2
 
 Create a database for taking notes.
 
-* What are the columns that a note table needs?
+- What are the columns that a note table needs?
 
-* If you have a timestamp field, how do you auto-populate it with the date?
+- If you have a timestamp field, how do you auto-populate it with the date?
 
-* A note should have a foreign key pointing to an author in an author table.
+- A note should have a foreign key pointing to an author in an author table.
 
-* What columns are needed for the author table?
+- What columns are needed for the author table?
 
 Write queries that:
 
-* Insert authors to the author table.
+- Insert authors to the author table.
+
+- Insert notes to the note table.
 
-* Insert notes to the note table.
+- Select all notes by an author's name.
 
-* Select all notes by an author's name.
+- Select author for a particular note by note ID.
 
-* Select author for a particular note by note ID.
+- Select the names of all the authors along with the number of notes they each have. (Hint: `GROUP BY`.)
 
-* Select the names of all the authors along with the number of notes they each have. (Hint: `GROUP BY`.)
+- Delete authors from the author table.
 
-* Delete authors from the author table.
   > Note that SQLite doesn't enforce foreign key constrains by default. You have
   > to enable them by running `PRAGMA foreign_keys = ON;` before your queries.
-
-  * What happens when you try to delete an author with an existing note?
-  * How can you prevent this?
+
+  - What happens when you try to delete an author with an existing note?
+    In my case nothing, since I enabled foreign keys before trying this.
+    I don't think I'd want to prevent this behaviour ^^
+  - How can you prevent this?
 
 Submit a file `notes.sql` with the queries that build (`CREATE TABLE`/`INSERT`)
 and query the database as noted above.
-

day1.sql

@@ -0,0 +1,68 @@
+-- Show all albums.
+SELECT * FROM album;
+
+-- Show all albums made between 1975 and 1990.
+SELECT * FROM album
+WHERE (release_year <= 1990)
+AND (release_year >= 1975);
+
+-- Show all albums whose names start with `Super D`.
+SELECT * FROM album
+WHERE title LIKE "Super D%";
+
+-- Show all albums that have no release year.
+SELECT * FROM album
+WHERE release_year IS NULL;
+
+
+-- Show all track titles from `Super Funky Album`.
+SELECT track.title, album.title from track
+JOIN album ON(album.title = "Super Funky Album");
+--OR
+SELECT track.title FROM track,album 
+WHERE album.title = 'Super Funky Album' 
+AND album_id = album.id;
+
+-- Same query as above, but rename the column from `title` to 
+-- `Track_Title` in the output.
+SELECT track.title AS Track_Title
+from track
+JOIN album ON(album.title = "Super Funky Album");
+-- OR
+SELECT track.title AS Track_Title
+FROM track,album 
+WHERE album.title = 'Super Funky Album' 
+AND album_id = album.id
+
+-- Select all album titles by `Han Solo`.
+
+SELECT album.title AS Album_Title
+from album
+JOIN artist ON(artist.name = "Han Solo");
+-- OR 
+SELECT * FROM artist, artist_album 
+WHERE artist.id = artist_id 
+AND artist.name= 'Han Solo';
+
+-- Select the average year all albums were released.
+SELECT avg(release_year)
+FROM album;
+
+-- Select the average year all albums by `Leia and the Ewoks` were released.
+
+SELECT AVG(release_year) 
+FROM artist, album, artist_album 
+WHERE artist.id = artist_album.artist_id
+AND album.id = artist_album.album_id 
+AND artist.name = 'Leia and the Ewoks';
+
+-- Select the number of artists
+
+SELECT count(id)
+FROM artist;
+
+-- Select the number of tracks on `Super Dubstep Album`.
+
+SELECT count(track.id)
+FROM track, album
+WHERE album.title = "Super Dubstep Album";

notes.sql

@@ -0,0 +1,58 @@
+-- create an author table with needed data
+
+create table author (
+id INTEGER PRIMARY KEY AUTOINCREMENT,
+name VARCHAR(128) NOT NULL
+);
+
+-- create a notes table including an autopopulated date field
+-- and a foreign key referencing the author
+
+create table note (
+id INTEGER PRIMARY KEY AUTOINCREMENT,
+title VARCHER(128) NOT NULL,
+body VARCHAR(2056) NOT NULL,m
+author_id INTEGER REFERENCES authod(id),
+timestamp DATE DEFAULT (datetime('now', 'localtime'))
+);
+
+-- fill db with authors
+
+INSERT INTO author VALUES ("Peter");
+INSERT INTO author VALUES ("Klaus");
+INSERT INTO author VALUES ("Margareth");
+INSERT INTO author VALUES ("Ursula");
+INSERT INTO author VALUES ("Petra");
+
+-- fill db with notes
+
+INSERT INTO note (title, body, author_id) VALUES("blubb1", "blalbalbab1", 1);
+INSERT INTO note (title, body, author_id) VALUES("blubb2", "blalbalbab2", 2);
+INSERT INTO note (title, body, author_id) VALUES("blubb3", "blalbalbab3", 3);
+INSERT INTO note (title, body, author_id) VALUES("blubb4", "blalbalbab4", 4);
+INSERT INTO note (title, body, author_id) VALUES("blubb5", "blalbalbab5", 5);
+INSERT INTO note (title, body, author_id) VALUES("blubb6", "blalbalbab5", 1);
+INSERT INTO note (title, body, author_id) VALUES("blubb7", "blalbalbab5", 2);
+
+-- select all notes by author "Peter"
+
+SELECT name, title, body,  timestamp FROM note, author
+WHERE author.name = "Peter"
+AND author.id = author_id;
+
+-- select author of note nr 3 
+
+SELECT author.name FROM author, note
+WHERE note.id = 3 and
+author.id = author_id;
+
+-- count notes and group by author
+
+SELECT name, count(title) FROM note, author
+WHERE author.id = author_id
+GROUP BY author.name;
+
+-- delete author 
+
+DELETE FROM author
+WHERE name = "Peter";